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Topics - Elgen

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ARCADE / Psychic5 video distortion. Input needed! };-S
« on: March 06, 2013, 07:10:03 PM »
Hey Mates

I currently have a bootleg Psychic5 on the table. I've made some repairs in the controls/input section and made a JAMMA-adaptor, and it now plays perfectly.

HOWEVER, there are some small, tho rather annoying, distortions in the upper part of the screen.
It looks like small white stripes about ½-1cm long (in the direction of the scanlines) and 1pixel wide. They only apear during gameplay (or gameplay-part of the attract-mode), and not all the time.

I've to take 2 stills of it with my iPhone





I've also shot a small video of it

http://www.youtube.com/watch?v=MOPsOnKEqCM

The board is 2 PCBs with ribbons, and video is generated on the secondary PCB. The fault is definitly on the second board, cause I've got another Psychic5 (maby original?) with identical secondary PCB. And if I swap the PCBs, the error swaps as well.

I've traced the R/G/B and SYNC lines back på this section on the secondary board; actually they go directly to some of the resistors



Another piece of info is, that this game can flip the screen via dip switch, and when I do so, the interference still appear in the same physical place on the screen (top); it doesn't flip along with the picture.

I'm pretty sure, that this interference is induced into the video signal during the very last steps of the video generation, as it looks like affects both back grounds and sprites, but that is just my feeling...could be wrong.

This is really starting to annoy me, so any input would be nice.

Also, should anyone have a scan of the schematics for the game, I would be very glad to get a copy; haven't been able to find it via googling.

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ARCADE / Seeking: Bootleg SuperQIX; not for buying, but for a ROM dump...
« on: February 02, 2013, 11:41:15 AM »
Ok, my problem is this. I was trying to fix a bootleg SuperQIX with sprite errors. During this, I had one of the ROMs out of the socket (and forgot to dumpd it). Now the clown who fitted this socket, had soldered it in backwards. So when I put the ROM back, it was actually reversed resulting in it getting fried. As I didn't have a dump of the ROM, I was basicly screwed. I have tried all the different dumps in MAME, but can't find one that works on my board.

This is how the board looks


and the ROM in question is the one in the upper rigth corner; here's a close-up


The ROM is an 2732. So if you have this board, or one that looks like it, I would be very glad to get a dump of this IC. Otherwise, this board is just for the scrap-pile...

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ARCADE / Best way to debug a stuck bus line?!
« on: January 26, 2013, 10:40:02 AM »
Okay, here's the situation:
I'm currently working on a bootleg 1942 where the only initial problem was that some of the controller lines was stuck low causing the plane to go left and use all rolls at start-up. That fix was easy: Changed a couple of fried 367's in the input section.
However while working on it, I suddenly lost all sound?! I don't think it's related to the input problem at all, just a coincidence.
The sound CPU is a Z80 controlling 2 AY-3-8910 via the Z80's databus. On the same bus is also an SRAM and the sound ROM. Now one of the 8 lines is stuck low (one right in the middle). That is it fluctuates between GND and 0.5V, so it looks to me like something is trying to drive it. It also have direct contact to GND (used continuity tester). But I can't seem to find the component that's pulling it down. Tried to cut the relevant pins on both the AYs, the ROM (just pulled it from the socket), the RAM, the CPU, and also a 374 I found to be on the bus. I would rather avoid desoldering the CPU and the AYs.
As bonus info I have a working SolomonsKey with 3 of the same sound chips, and here ALL datalines are active.
By the way, the way I tried to find ICs and components that connects to the stuck, is by starting at the AYs and beeping the healthy bus line just besides the stuck one around the PCB and then looking if data pins 'close to' it on the ICs I found were stuck low.

Where would go next? Is it desoldering the AYs and CPU to see how the circuit is under them, or is there more to check before that?

Any help could be useful };-P

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FOR SALE / WANTED / WTB: Pods for Fluke9010A
« on: December 01, 2012, 12:07:15 PM »
Just got a 9010A base unit, but have no pods.
I'd really like a Z80, a 68000, and a 6502, but atm anything have my interest. Working or defective doesn't matter, I'm interested.

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ARCADE / Mitchell Funky Jet Bootleg Repair Log
« on: August 12, 2012, 05:37:53 PM »
Well, some repairs are very easy, and this one happens to be one of them...in fact the hardest part of this rep, actually was to get the photos right for this log.
Well I was given this board, along with some other defective ones, as payment for burning some EPROMs for this dude I know from spille-maskiner.dk. When first hooked up, the game seemed to play fine and the sound was fine too. But at the intro (where the two main characters of the game fly past each other) and at the stage select screen the graphics was messed up.







During visual inspection of the board, tahn infacts looks to be in pretty good overall condition, I noticed an IC with two caps soldered over the top of it. One of them had one pin broken loose from the IC.



(here I have yanked it a bit to make a point };-P)
I pressed it against the IC pin with my finger, and







Fired up that old soldering iron...a few drops of solder...



...and VIOLA...board fixed };-P

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ARCADE / Extending the usage of a cheap Top2005+ programmer
« on: June 25, 2012, 01:35:28 PM »
I have finally finished a blogpost about my latest project: Enable a Top2005+ (cheap chinese EPROM programmer) to program 16bit EPROMs and test 4bit SRAMs (something that software it ships with can't do).

Comments etc. in this thread, but also especially on the blog, are more than welcome. };-P

http://elgensrepairs.blogspot.dk/2012/05/extending-usage-of-top2005-universal.html

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